The present invention relates to a charge coupled device mold package structure with an improved heat radiation structure, and more particularly to a mold package structure with an improved heat radiation structure for a one-dimensional charge coupled device.
It has been known that as a temperature of the semiconductor device is increased, then a leakage of current of the semiconductor device is also increased. If the charge coupled device is increased in temperature, then the leakage of current of the device is also increased. The increase in the leakage of current causes a dark output. The one-dimensional charge coupled device has a single alignment of many pixels, for example, about 5000 pixels, wherein the single alignment has a first end provided with an amplifier and a second end opposite to the first end. Many photo-receiving transistors are aligned from the first end to the second end of the single alignment of the pixels. Pixels near the amplifier are likely to be increased in temperature. A difference in temperature between the aligned pixels occurs. Namely, non-uniform temperature distribution over the single alignment of the pixels occurs. This non-uniformity in temperature over the single alignment of the pixels causes non-uniformity of the dark output due to the non-uniform leakage currents. Even if the pixel receives no light, then the dark current flows through the pixel so that the pixel is placed in almost the same state as when the pixel receives a light. This results in deterioration in quality of the image generated by the charge coupled device. For the conventional product of 300 DPI (dots per inch), the variation or non-uniformity of the dark output is not much of a problem. However, the advanced charge coupled device of not less than 600 DPI has a strict requirement for suppressing the variation or non-uniformity to the dark output due to the temperature variation over the positions of the aligned pixels. Namely, the advanced charge coupled device of not less than 600 DPI needs a uniform temperature distribution over the positions of the aligned pixels. The conventional mold package for the charge coupled device has less capability of heat radiation. It is necessary for the advanced charge coupled device, particularly the advanced one-dimensional charge coupled device, to develop a novel mold package structure improved in heat radiation capability.
In the above circumstances, it had been required to develop a novel mold package structure with an improved heat radiation structure for an advanced charge coupled device particularly advanced one-dimensional charge coupled device free from the above problems.
Accordingly, it is an object of the present invention to provide a novel mold package structure with an improved heat radiation structure for an advanced charge coupled device, particularly an advanced one-dimensional charge coupled device, free from the above problems.
It is a further object of the present invention to provide a novel heat radiation structure of a mold package structure for an advanced charge coupled device, particularly an advanced one-dimensional charge coupled device, free from the above problems.
The first present invention provides a heat radiation structure of a mold package for a semiconductor device. The heat radiation structure comprises: an island of a lead frame having a high heat conductivity for mounting a semiconductor device; outside leads having a high heat conductivity and extending outwardly from the island; and at least a connective region having a high heat conductivity for electrically and thermally connecting the island to the outside leads.
The second present invention provides a mold package for a semiconductor device. The mold package comprises: a mold body for sealing a semiconductor device; a lead frame having a high heat conductivity for mounting the semiconductor device; a cap for covering a top opening of the mold body; and a bottom sealing member for sealing a bottom opening of the mold body, wherein the lead frame further has: an island for mounting the semiconductor device; outside leads extending outwardly from the island; and at least a connective region for electrically and thermally connecting the island to the outside leads.
The above and other objects, features and advantages of the present invention will be apparent from the following descriptions.